4-hydroxy-6-alkyl-1, 3, 3alpha, 7-tetrazaindene stabilizers for photographic emulsions sensitized with polyalkylene esters, amides, and ethers



United States PatentO 4-HYDROXY-6-ALKYL 1,3,3a,7 TETRAZAINDENE STABILIZERS FOR PHOTOGRAPHIC EMUL- SIONS SENSITIZED WITH POLYALKYLENE ESTERS, AMIDES, AND ETHERS No Drawing. Application April 29, 1954, Serial No. 426,545

This invention relates to fog inhibiting agents and stabilizers for photographic emulsions and to photographic emulsions containing them.

This application is a continuation-in-part of our application Serial No. 365,550, filed July 1, 1953, now U. S. Patent 2,716,062.

It is well known that photographic emulsions on storage tend to lose sensitivity and to become spontaneously developable without exposure to light. There is normally a detectable amount of the silver salt reduced during development in the areas where no exposure was given; this is commonly called fog, and sometimes called chemical fog where it is necessary to distinguish between it and the efiects ofaccidental exposure to radiation; in this invention, we are not concerned with the latter.

Fog depends both on the emulsion and the conditions of development; for a given emulsion it increases with the degree of development. With constant development conditions, .it tends to increase with time, temperature and climates, for example. Fog usually appears over the whole area of the .sensitive coating, but when severe, it frequently is non-uniform. Fog may .also be-caused ,by exposure to chemicals, for example, hydrogen sulfide and other reactive sulfur compounds, hydrogen peroxide vapor, and strongly reducing materials. While antifoggants and "stabilizers may protect, to someextent, against suche'fiects,

it is normally understood that an antitoggant protects against spontaneous growth of fog during prolonged storage or storage at high temperatures and humidities,

or during development to maximum contrast and speed,

or both.

It is known that the .efiective sensitivity :of photographic silver halide emulsions may .be increased .by

adding to them derivatives .of alkylene .oxides such as ethylene oxide polymers having molecular weights of 300 or more. The practical value of these compounds 'is severely limited by their tendency to increase fog on storage of the photographic film, especially storage at elevated temperatures and humidities. 'It hasbeen found diflicult to control this by the antifoggants commonly available without using quantities of cantifoggant which partly neutralize the speed increase obtained from the" alkylene oxide derivatives.

It is therefore an .object of the present invention to provide a method for stabilizing photographic emulsions sensitized with alkylene oxide derivatives such as polyethylene oxides. A further object is to provide a means ,for reducing the fog produced under keeping of emulsions so sensitized, especially emulsions stored under tropical.orotheradverse conditions A still'further object is to provide a means -for stabilizing the speed and Cit butylene oxide.

2 contrast .of emulsions so sensitized. Other objects will appear from the following description of our invention.

These objects are accomplished in general by adding 4 hydroxy 6 alkyl l,3,3a,7 tetrazaindenes as stabilizing and fog inhibiting agents, to silver halide emulsions sensitized with condensation products of alkylene oxides with aliphatic acids, aliphatic amines orphenols. 7 cases the emulsion may be sensitized with the alkylene oxide condensation products without adding the stabilizing agent.

The alkylene oxidepolymers used to sensitize the emulsions may beof various types. The alkylene oxidesfrom which the polymers are derived contain from 2 to 4carbon atoms, e. g., ethylene oxide, propylene oxide and The preparation of polymers from .these compounds is described in Ellis, The Chemistry ofsynthetic .Resins 1935), pages 990 to 994. These compounds are also referred to as polya'lkylene glycols and their use as sensitizers for silver halide emulsions is .described in U. S. Patents 2,423,549 and 2,441,389.

, The alkyleneoxide condensationproducts include condensation products of alkylene .oxides with aliphatic acids, .e. g, lauric acid and glycine, condensation products of alkylene oxides with aliphatic amines or amides, e. g., glycine and lauryl amide, and condensation prodnets of alkylene oxides with phenols, e. g., phenol itself. The preparation of these condensation products is .described in U. S. Patent 1,970,578 and in Carroll U. S. application Serial No. 426,543,.now Patent No. 2,743,180, filed concurrently herewith.

In each case the polyalkylene oxide or derivative of alkylene oxideshould have a molecular weight of at least 300 and preferably a molecular weight of -1500:t,o

4000 or more. 7

'The tetrazaindene stabilizing agents which we propose to use have the following probable structure:

-R-O o OH in whichRis an alkyl group, e. g. methyl, ethyl, propyl,

. butyl, etc. i

The compounds of our invention may be prepared by heating ethyl acetoacetate or'its homologues with 3-amino- 1,2,4-triazole. (Ber. 42, Part 4, page 4642, 1909;

'Zeitschrift fiir wissenschaftliche Photographic, 47, part '1-8, page '6, 1952.) While the literature indicates that this reaction produces compounds having the general formula expressed above and the specific formula which :follows, weinclude within the scope of our invention any isomeric or tautomeric forms of the compounds which may be'produced by this reaction and which are effective fog-inhibiting.orstabilizing agents for photographic emuli-h dt-ox -s-metnyi-rs.sanaetrszsiadene (6-methy1-1,3-triarc-1,0-pyrimidine-.4hydroxy1ic acid) HaC- ,The principal purpose of our inventionds 1. .P TQ-Y dm means for maintaining the sensitivity and ;fo g. of silver halide, emulsionsat or close to initial optimum -values under conditions of high temperature or humidity or both. Preferably the "fog inhibitors which we propose In some The tetrazaindene fog inhibitor may be added to the" emulsion in solution in any convenient solvent not in- 4 2,728,663, Carroll and Murray U. S. Patent 2,728,664 and Leubner and Murray U. S. Patent 2,728,665.

The sensitizing and stabilizing combinations of polyalkylene oxides and tetrazaindenes are effective in the (Lowe and Jones U. S. Patent 2,521,926). The emulsions may also be stabilized with the mercury compounds of Allen, Byers and Murray U. S. Patent 75 jurious to the emulsion such as lower alcohols or ketones. 5 presence or absence of optical sensitizing dyes. Since A solution of the tetrazaindene which we employ when optical sensitizing may afiect stability of emulsions with added in suitable concentration before coating to unrespect to sensitivity, fog and latent image changes, the sensitized or optically sensitized silver halide emulsions action of the compounds of this invention is not comusually does not appreciably affect the sensitivity and pletely independent of optical sensitizing or other emulfog when measurements are made soon after coating. sion variables. We have found, however, that both un- HOWCVBI, when Sensitomeiric measurements are made sensitized emulsions and emulsions sensitized with after appreciable intervals of time under tropical or dry cyanine or merocyanine dyes or both may be treated with Conditions Of Storage at elevated temperatures, these polyalkylene oxides and tetrazaindenes according to our pounds do stabilize speed and maintain fog at a low level. inventi n,

- The preparation of silver halide emulsions involves The most useful concentration of the tetrazaindene com- Separate Operations! the emulsificafion and pound in the emulsion is from about 0.1 gram to 4 grams fligeetien or ripening of the silver halide. the i g per ram mole of silver halide in the emulsion. Al- Of the emulsion from aqueous Soluble Salts usually y though higher amounts may be used, no emulsion is likewashing. the second digestion or after-ripening to 1y to tolerate as much as 5 times this upper limit without Obtain increased Sensitivity The Theory Of the serious desensitization. Optimum concentrations are Photographic Process, 1942, P The fog inhibiting about 2.0 gram of the tetrazaindene per gram mole of agents y be added at any Stage, Preferably after the silver halide. These amounts may be used in combinafinal digesiiofltion with one or more of the chemical sensitizing and The photographic emulsions which we use are of the bili i agents 1i b developing-011'! yp and best results have been Obtained The stabilizing action Was determined by incubation of with gelatino-silver bromoiodide emulsions. However, the emulsions usually for one or two eeks at 120 emulsions 0f Varying halide Content y be usedand constant humidity unless otherwise stated in the ex- The emulsions y be chemically sensitized y y amples. The results of aging tests are tabulated below of the accepted procedures, in addition to or in combinad compare speed, gamma d f f h emulsions i h tion with the sensitizing with alkylene oxide polymers. d i h h bili i compound, The emulsions may be digested with naturally active gelatin, or sulfur compounds may be added such as those Example 1 described in Sheppard U. S. Patents 1,574,944 and One liter of anegative speed gelatino-silver bromoiodide 1,623,499, and Sheppard and Brigham U. S. Patent emulsion was digested with a sulfur compound such as 2,410,689. disclosed in Sheppard U. S. Patent 1,574,944 and potas- The emulsions may also be treated with salts of the sium chloroaurate and optically sensitized with 80 mg. noble metals such as ruthenium, rhodium, palladium, of 3,3-diethyl 9-methylthiacarbocyanine bromide per iridium and platinum, all of which belong to group VIII mole of silver halide. To a portion of the emulsion there of the periodic table of elements andhave an atomic were added 2 grams per gram mole of silver halide of weight greater than 100. Representative compounds are the lauric acid ester of polyethylene oxide made by conammonium chloropalladate, potassium chloroplatinate densing 1 mole of lauric acid with approximately 26 and sodium chloropalladite, which are used for sensitizmoles of ethylene oxide. To a portion of this latter ing in amounts below that which produces any substantial emulsion there was added 0.8 gram per gram mole of fog inhibition, as described in Smith and Trivelli U. S. silver halide of 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene. Patent 2,448,060, and as antifoggants in higher amounts, The emulsions were coated on film base and were as described in Trivelli and Smith U. S. Patents 2,566,245 exposed on an Eastman type Ib Sensitometer and deand 2,566,263. veloped for 6% minutes at 68 F. in a developer of the The emulsions may also be chemically sensitized with following formula:

gold salts as described in Waller and Dodd U. S. Patent 2,399,033, or stabilized with gold salts as described in so g' gf i sulfate ff Damschroder U. S. Patent 2597856 and Yutzy and y oqumone n Sodium sulfite (desiccated) do 75 Leermakers U. S. Patent 2,597,915. Suitable compounds Borax do 4 s are potassium chloroaurite, potassium aurithiocyanate, Potassium bromide potassium chloroaurate, auric trichloride and 2-auro- W t t sulfobenzothiazole methochloride. a er 0 M The emulsions may also be chemically sensitized with The films with and without the addenda were held at reducing agents such as stannous salts (Carroll U. S. 120 F. and constant humidity for one week and were Patent 2,487,850), polyamines such as diethylene triamine then exposed and developed as in the case of the un- (Lowe and Jones U. S. Patent 2,518,698), polyamines such incubated samples. The results of tests for speed, gamma as spermine (Lowe and Allen U. S. Patent 2,521,925), or and fog were as follows:

Fresh Test After Incubation Compound Agent per mole Emma Speed Gamma Fog Speed Gamma Fog Control- 2, 700 0. 68 0. 10 1, 470 0. 5s 0. 14 Polyethylene oxide laurlc ester (I) 2 4,350 68 10 2, 500 55 19 intaz'raatniiii::::::::::::::::::

bis(fl-aminoethyl) sulfide and its water-soluble salts Example 2 Coatings were made and tested as in Example 1, using instead of the lauric ester of polyethylene oxide, one gram per gram mole of silver halide of the phenol ether of polyethylene oxide, made 'by condensing one mole of phenol with approximately 28 moles of ethylene oxide. Results of tests for speed, gamma and fog were as follows:

l. A light-sensitive silver halide emulsion sensitized with a condensation product of 6 to '50 moles of an alkylene oxide with 1 mole of a compound selected from the Fresh Test After Incubation Compound Agent per mole, grams Speed Gamma Fog Speed Gamma Fog Control 2, 700 o. as o. 1, 470 0. 5e 0. 14 Polsitithylene oxide phenol ether (II) 1 3, 800 67 10 .50 5 5 1-7 Tetmzaindene 8 j 350 61 10 100 60 .1

Example 3 instead of thel a'uric ester of polyethylene oxide, one gram per gram mole of silver halide of the condensation product of one mole of glycine with approximately 20 moles of ethylene oxide. Results of tests for speed, gamma and fog were as follows:

class consisting of lauric acid, lauryl amide, glycine and Coatings were made and tested as in Example 1, using Phenol Said alkylene oxidvelcontaining from 2 to 4 QarbQn atoms and said condensation product having a molepu'lar weightof at least 300 I I 2. A light-sensitive silver "halide emulsion-sensitized with a condensation product of 6 to 50 moles of ethylene oxide with 1 mole of a compound selected from the class Fresh Test After Incubation Compound Agent per mole, grams Speed Gamma Fog Speed Gamma Fog Control 2, 700 0. 68 0. l0 1, 470 0. 56 0. 14 Polyititlhylene oxideglycine (III). I 3, 500 67 10 2,000 57 i 17 ret'ra'z'dihiiiell:IIIIIIIIIIj .8 i 13 Example 4 Coatings were made and tested as in Example 1, using instead of the lauric ester of polyethylene oxide, one gram per gram mole of silver halide of the condensation prodnot of one mole of lauryl amide with approximately 20 moles of ethylene oxide. gamma and fog were as follows:

consisting of lauric acid, lauryl amide, glycine and phenol, said condensation product having a molecular weight of at least 300.

3. A light-sensitive silver halide emulsion sensitized with an ethylene oxide polymer which is a condensation Results of tests for speed, product of one mol of lauric acid with approximately 26 moles of ethylene oxide, said emulsion containing as a Fresh Test After Incubation Compound Agent per mole. grams Speed Gamma Fog Speed Gamma Fog Control 2, 700 0. 68 0. 10 1, 470 0. 56 0. 14 Polyiexthylene oxidelaurylamide (IV) i 3, 800 70 10 1, 690 .57 20 Teirliiaiiih'eliilfiIIIIIIIIIIIIIII .s i 13 The polyethylene oxide polymers used in the emulsions according to our invention may be prepared either by polymerizing ethylene oxide in the presence of aliphatic acids, aliphatic amines, or phenols, or by reacting the polymerized polyethylene oxide with aliphatic acids, acid chlorides, or esters, which produces similar products.

Instead of incorporation in the silver halide emulsion the fog-inhibitors of our invention may be incorporated in a colloid layer such as a gelatin layer in contact with the emulsion.

The fog-inhibiting agents which we have described may be used in various kinds of photographic emulsions. In addition to being useful in non-sensitized emulsions they may also be used in orthoch-romatic, panchromatic and X-ray emulsions. If used with sensitizing dyes, they may be added to the emulsion before or after the dyes are added. Various silver salts may be used as the sensitive s'alt, such as silver bromide, silver iodide, silver chloride or mixed silver halides. The azaindene compounds and alkylene oxide polymers may be used in emulsions intended for color photography, for example, emulsions containing color-forming couplers, or emulsions to be developed by solutions containing couplers.

The dispersing agents may be gealtin or other colloid such as collodion, albumen, cellulose derivatives or synthetic resins.

It will be understood that we contemplate as included within our invention all modifications and equivalents falling within the scope of the appended claims.

We claim:

fog-inhibiting agent zaindene.

4. A light-sensitive silver halide emulsion sensitized with an ethylene oxide polymer which is a condensation product of one mol of glycine with approximately 20 moles of ethylene oxide, said emulsion containing as a fog-inhibiting agent 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene.

5. A light-sensitive silver halide emulsion sensitized with an ethylene oxide polymer which is a condensation product of one mol of lauryl amide with approximately 20 moles of ethylene oxide, said emulsion containing as a fog-inhibiting agent 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene.

6. A light-sensitive silver halide emulsion sensitized with an ethylene oxide polymer which is a condensation product of one mol of phenol with approximately 28 moles of ethylene oxide, said emulsion containing as a fog-inhibiting agent 4-hydroxy-6-methyl-l,3,3a,7-tetrazaindene.

7. A light-sensitive sulfur-sensitized silver halide emu1- sion additionally sensitized with an ethylene oxide poly mer which is a condensation product of one mol of lauric acid with approximately 26 moles of ethylene oxide, said emulsion containing as a fog inhibiting agent 4-hydroxy- 6-methyl-1,3,3a,7-tetrazaindene.

8. A light-sensitive sulfur-sensitized silver halide emul+ sion additionally sensitized with an ethylene oxide poly mer which is a condensation product of one mol of glycine with approximately 20 moles of ethylene oxide, said emul- 4-hydroxy-6-methyl-1,3,3a,7-tetra 7 sion containing as a fog inhibiting agent 4-hydroxy-6- methyl-l,3,3a,7-tetrazaindene.

9. Azlight-sensitive sulfur-sensitized silver halide emulsion additionally sensitized with an ethylene oxide polymer which is a condensation product of one mol of lauryl amide with approximately 20 moles of ethylene oxide, said emulsion containing as a fog inhibiting agent 4-hydroxy- 6-methyl-1,3,3a,7-tetrazaindene.

10. A light-sensitive sulfur-sensitized silver halide emulsion additionally sensitized with an ethylene oxide polymer which is a condensation product of one mol of phenol with approximately 28 moles of ethylene oxide, said emulsion containing as a fog inhibiting agent 4-hydroxy-6- methyl-1,3,3a,7-tetrazaindene.

l1. The emulsion of claim 7 which is additionally chemically sensitized with gold salts.

12. The emulsion of claim 8 which is additionally chemically sensitized with gold salts.

13. The emulsion of claim 9 which is additionally chemically sensitized with gold salts.

14. The emulsion of claim 10 which is additionally chemically sensitized with gold salts.

References Cited in the file of this patent UNITED STATES PATENTS 1,970,578 Schoeller et al. Aug. 21, 1934 2,240,472 Swan Apr. 29, 1941 2,400,532 Blake et al. May 21, 1946 2,423,549 Blake et al. July 8, 1947 2,441,389 Blake May 11, 1948 2,449,225 Heimbach et al. Sept. 14, 1948 2,450,397 Heimbach Sept. 28, 1948 2,716,062 Carroll et al. Aug. 23, 1955 

1. A LIGHT-SENSITIVE SILVER HALIDE EMULSION SENSITIZED WITH A CONDENSATION PRODUCT OF 6 TO 50 MOLES OF AN ALKYLENE OXIDE WITH 1 MOLE OF A COMPOUND SELECTED FROM THE CLASS CONSISTING OF LAURIC ACID, ALURYL AMIDE, GLYCINE AND PHENOL, SAID ALKYLENE OXIDE CONTAINING FROM 2 TO 4 CARBON ATOMS AND SAID CONDENSATION PRODUCT HAVING A MOLECULAR WEIGHT OF AT LEAST
 300. 